CIR, 8-17 S, Segment 2

depth estimated from Fig. 2 in Son et al. (2014); Son et al. (2014): "Although only weak NTU anomalies were observed in segment 2, the existence of active venting was confirmed by clear ORP anomalies.", "four of five casts over a valley wall were identified as active plume sites. Thus, segment 2 would be regarded as a zone of no hydrothermal activity if observations were restricted to the axis only."; Kim (2010): "rock sampling and CTD casts and tows were performed in northern half of the multibeam survey area in the second leg (IR09 Leg2). Plume signatures were observed at all 5 surveyed segments, suggesting vigorous hydrothermal activities along the northern CIR. However, the optical signals (light transparency and backscattering) of the nearly every cast along the axial valley of the CIR showed increased background level, which might be due to higher level of suspended particles within the axial valley not only by widespread hydrothermal plumes but also by other processes like resuspension. Onboard dissolved methane analysis indicates that the greater part of the plume signals are originated from hydrothermal venting, not by resuspension."